CVE-2021-47189 (GCVE-0-2021-47189)

Vulnerability from cvelistv5 – Published: 2024-04-10 18:56 – Updated: 2025-05-04 07:06
VLAI?
Title
btrfs: fix memory ordering between normal and ordered work functions
Summary
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix memory ordering between normal and ordered work functions Ordered work functions aren't guaranteed to be handled by the same thread which executed the normal work functions. The only way execution between normal/ordered functions is synchronized is via the WORK_DONE_BIT, unfortunately the used bitops don't guarantee any ordering whatsoever. This manifested as seemingly inexplicable crashes on ARM64, where async_chunk::inode is seen as non-null in async_cow_submit which causes submit_compressed_extents to be called and crash occurs because async_chunk::inode suddenly became NULL. The call trace was similar to: pc : submit_compressed_extents+0x38/0x3d0 lr : async_cow_submit+0x50/0xd0 sp : ffff800015d4bc20 <registers omitted for brevity> Call trace: submit_compressed_extents+0x38/0x3d0 async_cow_submit+0x50/0xd0 run_ordered_work+0xc8/0x280 btrfs_work_helper+0x98/0x250 process_one_work+0x1f0/0x4ac worker_thread+0x188/0x504 kthread+0x110/0x114 ret_from_fork+0x10/0x18 Fix this by adding respective barrier calls which ensure that all accesses preceding setting of WORK_DONE_BIT are strictly ordered before setting the flag. At the same time add a read barrier after reading of WORK_DONE_BIT in run_ordered_work which ensures all subsequent loads would be strictly ordered after reading the bit. This in turn ensures are all accesses before WORK_DONE_BIT are going to be strictly ordered before any access that can occur in ordered_func.
Severity ?
6.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
CWE
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 08a9ff3264181986d1d692a4e6fce3669700c9f8 , < bd660a20fea3ec60a49709ef5360f145ec0fe779 (git)
Affected: 08a9ff3264181986d1d692a4e6fce3669700c9f8 , < 637d652d351fd4f263ef302dc52f3971d314e500 (git)
Affected: 08a9ff3264181986d1d692a4e6fce3669700c9f8 , < 804a9d239ae9cbe88e861a7cd62319cc6ec7b136 (git)
Affected: 08a9ff3264181986d1d692a4e6fce3669700c9f8 , < ed058d735a70f4b063323f1a7bb33cda0f987513 (git)
Affected: 08a9ff3264181986d1d692a4e6fce3669700c9f8 , < 670f6b3867c8f0f11e5097f353b164cecfec6179 (git)
Affected: 08a9ff3264181986d1d692a4e6fce3669700c9f8 , < 6adbc07ebcaf8bead08b21687d49e0fc94400987 (git)
Affected: 08a9ff3264181986d1d692a4e6fce3669700c9f8 , < 47e6f9f69153247109042010f3a77579e9dc61ff (git)
Affected: 08a9ff3264181986d1d692a4e6fce3669700c9f8 , < 45da9c1767ac31857df572f0a909fbe88fd5a7e9 (git)
Create a notification for this product.
    Linux Linux Affected: 3.15
Unaffected: 0 , < 3.15 (semver)
Unaffected: 4.4.293 , ≤ 4.4.* (semver)
Unaffected: 4.9.291 , ≤ 4.9.* (semver)
Unaffected: 4.14.256 , ≤ 4.14.* (semver)
Unaffected: 4.19.218 , ≤ 4.19.* (semver)
Unaffected: 5.4.162 , ≤ 5.4.* (semver)
Unaffected: 5.10.82 , ≤ 5.10.* (semver)
Unaffected: 5.15.5 , ≤ 5.15.* (semver)
Unaffected: 5.16 , ≤ * (original_commit_for_fix)
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\"https://git.kernel.org/stable/c/bd660a20fea3ec60a49709ef5360f145ec0fe779\"}, {\"url\": \"https://git.kernel.org/stable/c/637d652d351fd4f263ef302dc52f3971d314e500\"}, {\"url\": \"https://git.kernel.org/stable/c/804a9d239ae9cbe88e861a7cd62319cc6ec7b136\"}, {\"url\": \"https://git.kernel.org/stable/c/ed058d735a70f4b063323f1a7bb33cda0f987513\"}, {\"url\": \"https://git.kernel.org/stable/c/670f6b3867c8f0f11e5097f353b164cecfec6179\"}, {\"url\": \"https://git.kernel.org/stable/c/6adbc07ebcaf8bead08b21687d49e0fc94400987\"}, {\"url\": \"https://git.kernel.org/stable/c/47e6f9f69153247109042010f3a77579e9dc61ff\"}, {\"url\": \"https://git.kernel.org/stable/c/45da9c1767ac31857df572f0a909fbe88fd5a7e9\"}], \"x_generator\": {\"engine\": \"bippy-9e1c9544281a\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbtrfs: fix memory ordering between normal and ordered work functions\\n\\nOrdered work functions aren\u0027t guaranteed to be handled by the same thread\\nwhich executed the normal work functions. The only way execution between\\nnormal/ordered functions is synchronized is via the WORK_DONE_BIT,\\nunfortunately the used bitops don\u0027t guarantee any ordering whatsoever.\\n\\nThis manifested as seemingly inexplicable crashes on ARM64, where\\nasync_chunk::inode is seen as non-null in async_cow_submit which causes\\nsubmit_compressed_extents to be called and crash occurs because\\nasync_chunk::inode suddenly became NULL. The call trace was similar to:\\n\\n    pc : submit_compressed_extents+0x38/0x3d0\\n    lr : async_cow_submit+0x50/0xd0\\n    sp : ffff800015d4bc20\\n\\n    \u003cregisters omitted for brevity\u003e\\n\\n    Call trace:\\n     submit_compressed_extents+0x38/0x3d0\\n     async_cow_submit+0x50/0xd0\\n     run_ordered_work+0xc8/0x280\\n     btrfs_work_helper+0x98/0x250\\n     process_one_work+0x1f0/0x4ac\\n     worker_thread+0x188/0x504\\n     kthread+0x110/0x114\\n     ret_from_fork+0x10/0x18\\n\\nFix this by adding respective barrier calls which ensure that all\\naccesses preceding setting of WORK_DONE_BIT are strictly ordered before\\nsetting the flag. At the same time add a read barrier after reading of\\nWORK_DONE_BIT in run_ordered_work which ensures all subsequent loads\\nwould be strictly ordered after reading the bit. This in turn ensures\\nare all accesses before WORK_DONE_BIT are going to be strictly ordered\\nbefore any access that can occur in ordered_func.\"}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2024-11-04T12:01:11.187Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2021-47189\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2024-11-04T12:01:11.187Z\", \"dateReserved\": \"2024-03-25T09:12:14.113Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2024-04-10T18:56:28.194Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.1"
    }
  }
}


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Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.